In waste treatment ponds and lakes, aerobic microbes eat waste in the presence of dissolved oxygen, producing carbon dioxide (CO2) and waste sludge in the process. In turn, facultative organisms eat the waste sludge and expel liquefied waste. This liquefied waste provides nutrients for other organisms, which turn the liquefied waste into short chain volatile fatty acids (VFA). These VFA generally cause a drop in pH of the pond water towards approximately 5.5 (7.0 being the pH of pure water). Still other organisms process the VFA and produce acetic acid, which further depresses the pH of the water to below 5.5. Methanogenic microbes reduce the acetic acid to methane and CO2. With the acetic acid being broken down, the pH of the water once again begins to rise. This process occurs naturally in healthy bodies of water; and is mimicked in sewage treatment and pollution mitigation processes.
The process described above is in dynamic equilibrium where one process is dependent on the product of the preceding reaction. If any one reaction is overly encouraged, the system becomes unbalanced, leading to a break down in the efficiency of the water system to process out organic waste. In natural, as well as man-made, water systems, circulation of the water in the system is very important for maintaining the proper aeration of the water and functioning of the waste removal processes.
Responsive to the need for water circulation to increase dissolved oxygen levels and waste removal processes, circulation devices are often utilized in waste treatment ponds and in highly polluted lakes. However, these water circulation devices employ motors, which require a power source. Consequently, the conventional circulator devices are quite expensive, and thus prohibitive for widespread use especially in poorer regions that are most likely to have polluted bodies of water.